Eleven separate groups of individuals, purportedly exposed to asbestos fiber in a range of concentrations, were culled from 3000 consecutive autopsies at New York City's Mount Sinai Hospital, Elmhurst General Hospital and Bronx Veteran's Administration Hospital. Lung parenchyma obtained from 7 anatomical sites, from both lungs, were processed for histological evaluation and for the determination of their inorganic particulate contents. Utilizing a 175 micron-thick tissue stack, ashed residues were examined by phase contrast microscopy, at 440X magnifications, over 1 cm square areas. Asbestos bodies and uncoated fibers observed were recorded. Quantitation of these objects were obtained on each of 211 individuals making up these 11 subgroups. Data were obtained on insulation workers, shipyard workers, individuals who worked in the building trades, superintendants and maintenance workers, plumbers, automobile mechanics and garage attendants, truck drivers, taxi drivers, chauffeurs, white collar office workers (primarily male) and white collar and office workers, housewives (primarily female). Selected occupations appear to possess asbestos bodies and fibers in accordance with intensity of asbestos exposure. Observations suggest the following: 100% of the asbestos workers have asbestos bodies in their lung tissues, in high concentrations; 85% of the Navy yard workers (shipyards) have high concentrations of asbestos bodies in their lung tissues; 75% of concentration workers have asbestos bodies in their lung tissues; there is a range of occurrence of asbestos bodies in the intervening working groups down to "white collar workers". These later 9aterials must be statistically analyzed to determine if differences exist among these groups; some 30% of white collar, housewife females, have what appear to be asbestos bodies in their lung tissues. These data are being analyzed by parametric and non-parametric statistics to determine statistical levels of confidence concerning differences or similarities among the different groups.